This invention relates to security systems for vehicles such as automobiles, vans and trucks, and in particular a new and improved system for providing an indication when unauthorized entry into a vehicle is attempted.
There is a wide variety of vehicle security systems on the market today and perhaps the most common problem with most of these systems is that of false triggering, that is, an alarm is produced even though no entry into the vehicle has been attempted. This may occur as a result of over-sensitive detectors and/or inadequate discrimination against ambient activity. As a result of the high incidence of false triggering, one tends to ignore the alarm and thereby adversely affecting the protection afforded by the system.
Some existing security systems utilize noise detection for sensing unauthorized entry. However, these systems are particularly susceptible to false triggering from external noises, such as passing vehicles, construction work, sirens, rain, thunder and the like.
It is an object of the present invention to provide a new and improved vehicle security system which utilizes noise detection as one form of sensing, with discrimination incorporated in the noise detection system for separating signals resulting from actual intrusion activity and signals resulting from external sounds.
Another form of detection utilized in existing systems is based on changes in vehicle battery voltage resulting from courtesy lights and the like being energized by opening of a closure, such as a door, the hood or the trunk lid. Of course, authorized entry also produces the same activity and hence some form of discrimination or inhibiting is required in a satisfactory system. Another problem arises in newer vehicles which have cooling fan activity after the motor has stopped, since turning on the fan motor produces a change in the battery voltage which is sensed. This activity produces false triggering unless some form of compensation is utilized.
It is another object of the invention to provide a new and improved vehicle security system incorporating battery voltage sensing while limiting triggering to lamp energization, discriminating against fan motor operation, and permitting authorized entrance without triggering of the alarm.
It is an additional object of the invention to provide such a vehicle security system which incorporates additional features including an audible alarm, a radio transmitted alarm, alarm timing, entrance and exit delays, and provisions for instant on operation and panic operation.
Other objects, advantages, features and results will more fully appear in the course of the following description.